Using Teiid 9.2.2 with postgresql, I issue a query structured like this:

(a
UNION ALL
b
UNION ALL
c)
INTERSECT
d

All queries are from a single database.
This query does not give back the expected result.

In the plan, I see the query printed with no parenthesis around the unions:
a UNION ALL b UNION ALL c INTERSECT d

This gives the same result as the query submitted with no parens in it (the intersect of c and d is unioned with a union b.

The expepeted result is to preserve the paren so that the intersect is performed against the union of all three tables.

As a note, using UNION instead of UNION ALL did not preserve the parens, either.